Navigating structure-kinetics-capacity trilemma for anode materials in sodium-ion batteries

Abstract

With the rapid development of an energy-consuming society, the modern world is eager for high-performance and low-cost energy storage technologies such as sodium-ion batteries (SIBs). The numerous proposals for SIB anode materials, however, are inherently governed by the Structure–Kinetics–Capacity (SKC) Trilemma, which captures the trade-off among structural integrity, fast sodiation/desodiation kinetics, and high specific capacity. This review critically analyzes recent progress in SIB anode engineering through the lens of this trilemma. We systematically deconstruct how intercalation, adsorption/desorption, alloying, and conversion anodes occupy distinct compromise regions, and we summarize how electrolyte-derived interphases modulate kinetics and stability across these classes. We then evaluate key engineering strategies, including nanosizing, carbon compositing, and electrolyte/interphase regulation, as targeted efforts to mitigate competing demands and expand the performance envelope, supported by a quantitative radar-plot benchmark with transparent normalization. To strengthen practical relevance beyond half-cell data, we discuss full-cell translation criteria, including N/P balancing, sodium inventory loss associated with low initial Coulombic efficiency (ICE), pre-sodiation and sodium-compensation routes, and cathode matching. We further compare dominant degradation mechanisms and clarify how structural and interphase instabilities trigger transport decay, polarization growth, and capacity fading within the trilemma framework. Finally, we outline future directions that may transcend conventional trade-offs, including atomically precise material design, operando characterization with multiscale modeling, scalable electrolyte-by-design, and emerging non-equilibrium synthesis such as high-temperature shock synthesis. By providing this unified conceptual framework, this review aims to guide the design of next-generation anodes that more holistically resolve the trilemma, propelling SIBs toward practical, high-performance energy storage.